A modified cellular automaton model for traffic flow on highway is proposed with a novel concept about the variable security gap. The concept is first introduced into the original Nagel-Schreckenberg model, which is c...A modified cellular automaton model for traffic flow on highway is proposed with a novel concept about the variable security gap. The concept is first introduced into the original Nagel-Schreckenberg model, which is called the non-sensitive driving cellular automaton model. And then it is incorporated with a sensitive driving NaSch model,in which the randomization brake is arranged before the deterministic deceleration. A parameter related to the variable security gap is determined through simulation. Comparison of the simulation results indicates that the variable security gap has different influence on the two models. The fundamental diagram obtained by simulation with the modified sensitive driving NaSch model shows that the maximumflow are in good agreement with the observed data, indicating that the presented model is more reasonable and realistic.展开更多
Determination of crop growth parameters of maize helps assess the performance of the crop for food security. A study was conducted in two seasons covering 2012 and 2013 to establish optimal irrigation and nitrogen fer...Determination of crop growth parameters of maize helps assess the performance of the crop for food security. A study was conducted in two seasons covering 2012 and 2013 to establish optimal irrigation and nitrogen fertilizer rates for drought tolerant hybrid maize （Zea mays L.）, DK8031 variety, in sandy loam soils using furrow irrigation. Four additive irrigation levels （119.05 mm, 238.10 mm, 357.15 mm and 476.2 mm） were allocated the main plots while five nitrogen fertilizer rates （0 kg/ha, 60, 75 kg/ha, 90 kg/ha and 100 kg/ha） were allocated the sub-plots. Both irrigation and nitrogen fertilizer treatments significantly enhanced crop growth parameters under consideration. Stand count per treatment plot, plant height and number of leaves per ranged from 45-59 plants/plot, 215-238 cm and 14-16 leaves respectively. It was concluded that use of supplementary irrigation and phased nitrogen fertilizer rates for maize growing in areas such as Embu can greatly promote crop growth.展开更多
Water plays an important role in food production especially rice. Rice productivity depends greatly on sufficient water to meet evaporative demand and soil moisture. It is certain thalL rice, the most important crop o...Water plays an important role in food production especially rice. Rice productivity depends greatly on sufficient water to meet evaporative demand and soil moisture. It is certain thalL rice, the most important crop of Thailand and Vietnam, is vulnerable to climate change. This paper proposes an analysis on the impact of climate on rice water requirement and food security in Thailand and Vietnam. Water demand, yield and production of rice were computed under the changed surface air temperature for three time slices, namely 2020s, 2050s and 2080s. Food security was analyzed from rice supply （calculated milled-rice product, rice stock, and imports） and demand （domestic uses from population growth, exports to world market, domestic seed and other uses）. The result showed that, under the higher surface air temperature scenario, water requirement office in Thailand and Vietnam could increase by 1.8 times in the end of the 21 st century. Production of rice dropped by declined yield. Thailand and Vietnam which is the world largest rice exporter in last decades will face the rice shortage in 2080s and 2030s respectively.展开更多
文摘A modified cellular automaton model for traffic flow on highway is proposed with a novel concept about the variable security gap. The concept is first introduced into the original Nagel-Schreckenberg model, which is called the non-sensitive driving cellular automaton model. And then it is incorporated with a sensitive driving NaSch model,in which the randomization brake is arranged before the deterministic deceleration. A parameter related to the variable security gap is determined through simulation. Comparison of the simulation results indicates that the variable security gap has different influence on the two models. The fundamental diagram obtained by simulation with the modified sensitive driving NaSch model shows that the maximumflow are in good agreement with the observed data, indicating that the presented model is more reasonable and realistic.
文摘Determination of crop growth parameters of maize helps assess the performance of the crop for food security. A study was conducted in two seasons covering 2012 and 2013 to establish optimal irrigation and nitrogen fertilizer rates for drought tolerant hybrid maize （Zea mays L.）, DK8031 variety, in sandy loam soils using furrow irrigation. Four additive irrigation levels （119.05 mm, 238.10 mm, 357.15 mm and 476.2 mm） were allocated the main plots while five nitrogen fertilizer rates （0 kg/ha, 60, 75 kg/ha, 90 kg/ha and 100 kg/ha） were allocated the sub-plots. Both irrigation and nitrogen fertilizer treatments significantly enhanced crop growth parameters under consideration. Stand count per treatment plot, plant height and number of leaves per ranged from 45-59 plants/plot, 215-238 cm and 14-16 leaves respectively. It was concluded that use of supplementary irrigation and phased nitrogen fertilizer rates for maize growing in areas such as Embu can greatly promote crop growth.
文摘Water plays an important role in food production especially rice. Rice productivity depends greatly on sufficient water to meet evaporative demand and soil moisture. It is certain thalL rice, the most important crop of Thailand and Vietnam, is vulnerable to climate change. This paper proposes an analysis on the impact of climate on rice water requirement and food security in Thailand and Vietnam. Water demand, yield and production of rice were computed under the changed surface air temperature for three time slices, namely 2020s, 2050s and 2080s. Food security was analyzed from rice supply （calculated milled-rice product, rice stock, and imports） and demand （domestic uses from population growth, exports to world market, domestic seed and other uses）. The result showed that, under the higher surface air temperature scenario, water requirement office in Thailand and Vietnam could increase by 1.8 times in the end of the 21 st century. Production of rice dropped by declined yield. Thailand and Vietnam which is the world largest rice exporter in last decades will face the rice shortage in 2080s and 2030s respectively.
